An ultrasonic probe using an ultrasonic transducer has been used for diagnosis of a tumor or the like in a human body by transmitting and receiving an ultrasonic wave.
An ultrasonic transducer using vibration of a piezoelectric body has been used. However, a capacitive micromachined ultrasonic transducer (CMUT) in which a vibration unit is manufactured on a silicon wafer has been actively developed for the purpose of practical use, as a result of advances in manufacturing techniques using a recent micro electro mechanical system (MEMS) technique. The CMUT has advantages in terms of a wide frequency band of an ultrasonic wave which can be used, and high sensitivity, compared to the ultrasonic transducer using the piezoelectric body in the related art. In addition, the CMUT is manufactured using an LSI processing technique, and therefore, it is possible to carry out microfabrication. As the related prior arts, there is, for example, PTL 1 or PTL 2 which has been previously filed by the inventor of this specification and relates to a simple structure of an ultrasonic transducer that improves the performance of ultrasonic wave transmission/reception.